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A Remark on Baserunning risk: Waiting Can Cost You the Game

We address the value of a baserunner at first base waiting to see if a ball in play falls in for a hit, before running. When a ball is hit in the air, the baserunner will usually wait, to gather additional information as to whether a ball will fall for a hit before deciding to run aggressively. This additional information guarantees that there will not be a double play and an "unnecessary out". However, waiting could potentially cost the runner the opportunity to reach third base, or even scoring on the play if the ball falls for a hit. This in turn affects the probability of scoring at least one run henceforth in the inning. We create a new statistic, the baserunning risk threshold (BRT), which measures the minimum probability with which the baserunner should be sure that a ball in play will fall in for a hit, before running without waiting to see if the ball will be caught, with the goal of scoring at least one run in the inning. We measure a 0-out and a 1-out version of BRT, both in aggregate, and also in high leverage situations, where scoring one run is particularly important. We show a drop in BRT for pitchers who pitch in more high leverage innings, and a very low BRT on average for "elite closers". It follows that baserunners should be frequently running without waiting, and getting thrown out in double plays regularly to maximize their chances of scoring at least one run.